"He's very, very weak on immigration and I'm very strong on
immigration," Trump
added in a CNN interview taped that day. "He believes in
amnesty strongly."

At another rally on Saturday, Trump and said he didn't believe
the recent polls that show him losing, and ripped into Carson on
various fronts.

"Who know what PACs are? It's a crooked business. It's a bad
business," he said. "They call them super-duper PACS. And they
put up millions and millions of dollars in these PACs. And those
PACs control the candidates, OK? They totally control — Carson is
controlled by his PAC."

Trump went on to hit several other top-tier candidates, including
former Florida Gov. Jeb Bush (R) and Sen. Marco Rubio
(R-Florida). But Trump seems particularly passionate about
attacking Carson.

At another point in his Saturday speech, Trump even appeared
to take a jab at Carson's faith while discussing the Iowa polls.
Carson attends a Seventh-day Adventist church, which Trump
suggested was less mainstream than his own Presbyterian one.

"I get these two polls — and remember, I don't believe them, I
don't believe them — in Iowa. And I love Iowa. And look, I don't
have to say it: I'm Presbyterian," he said. "I'm Presbyterian.
Boy, that's down the middle of the road folks, in all fairness. I
mean, Seventh-day Adventist, I don't know about. I just don't
know about."

The next day on ABC's "This Week," Trump insisted he was not
criticizing Carson's faith and would not apologize for his
comment.

"I would imagine and those people are using that PAC differently
than you're supposed to use a PAC. They are running Iowa for him.
They are in there, they're doing all sorts of things that are
totally different than what you're supposed to be doing," Trump
said, according to a CBS transcript.

He added: "And you know, Ben is in Iowa very little, he does not
go to Iowa much. The people are doing leaflets, they're doing all
this stuff. They're essentially campaigning for him in Iowa and
that's not what a PAC is supposed to be, it's not supposed to
happen that way."

"Ben is extremely weak, as you know, on illegal immigration and
you can't have that now. We have to have a country of borders. We
need strength in our country. And you can't be weak on illegal
immigration," Trump said.

Trump frequently brags that he's a "counter puncher" on the
campaign trial, only going after his rivals after they hit him
first. But it appears that Carson's support in the pair of Iowa
polls — one by
Bloomberg Politics/Des Moines Register and the other by
Quinnipiac University — was enough to make him a Trump
target.

Trump tweeted still more criticism against Carson on Sunday
morning:

Ben Carson has never created a job in his life (well, maybe a nurse). I have created tens of thousands of jobs, it's what I do.